UV light in Furnace?

Had our furnace and air ducts cleaned today for the first time in years; could have spun an entire dog from all the embedded hair. The serviceman tried to upsell me with both a new reusable filter (to get 94% of the airborne substances), and a UV light to be installed in the furnace to get the other 6% worth of mold spores, bacteria and no-seeums. I bought the filter and also a thorough cleaning of the furnace, but am waiting to decide on the UV light--another $400--until I can determine if this will really improve our indoor air quality. The house is 1000 sq ft, one dog and two dogwalkers live there. Any opinions? One dogwalker (me) has asthma. I couldn't find any research from a casual googling.

Since I posted, Jim Gunshinan sent me a link from the EPA website which basically says that UVGI cleaners for home use haven't been proven very effective yet for a number of reasons. They kill some organisms but not others. They recommend a HEPA filter in the furnace and says the following about mold removal--one of the benefits the serviceman claimed the lamp would have:

"No research or studies were found that show UV disinfection is effective in reducing dust mite and mold allergenicity or that UV radiation has the potential to remove gaseous pollutants. Because mold is allergenic, whether dead or alive, it can cause allergic reactions in sensitive populations. Therefore, UVGI cleaners might not be effective in reducing allergy and asthma symptoms. If mold is growing indoors, it should be removed."

Make sure to buy a Catalyst Based uv and not just a uv light. The catalyst based will produce ions that spread through the entire house. The uv light will only treat the exposed surface and not the air moving across, having very little effect. Also check the humidity levels. At 50% mold and bacteria won't grow. I use a phi cell along with a hepa filter in my home.

Adding a HEPA filter to the unit might not be wise. You want the correct filter for the correct airflow. You can pickup a stand alone HEPA filter for about 100 bucks. I have always been a fan a specific use products for specific tasks. This will go along way toward cleaning the air in your space. It uses less energy than the furnace.

While not very green of me I would prefer to discard filters and install new ones.

I would question why dog hair is making it to the ducts. With a properly installed filter on the return dog hair should not make it into the system. I have dogs cats and kids in a 1600 sq ft house with the doors an open door policy so the animals can come and go as they please. I have no hair in my ducts.

If you have a platform for your return I would suggest a new filter box grill and installing if the only filter is under the furnace itself. I would seal the return area with mastic and duct board if it is unconditioned space now

This makes it far easier to replace and will keep debris out of that space

I am not a fan of ozone, lights, ions or other such products and would never recommend them unless I get new information

I sincerely hope duct sealing is either being considered or has already happened as part of this process. Like Glen already mentioned, my primary concern would be how the mess got into your ductwork in the first place, and start there. It's worth asking why contractors that actively market duct cleaning and UV lights ignore that critical point. Source control, source control, source control.

My ducts are relatively new and all wrapped/sealed. The problem is that the cold air return is a floor grate in my 1926 bungalow and the hair just rolls in there like tumbleweed. We are thinking about getting screening mesh and placing it on the underside of the grate to prevent any more hair deposits, and vacuuming out weekly. I've decided against the UV light; am awaiting delivery of the new furnace filter.

The UV light in the recirculating pump in the small pond by the front door seems to really help keep the algae in check. I have installed several UV lights in the return air plenum of forced air heating systems. You're right, their about $400. Trouble is, you never really know if the light is helping the asthma patient. Can not whip out a testing tool and take a reading. Of the several I've installed, no one has gotten back to me and said,"Wow, I sure feel better." I don't install them anymore, I just increase the quality of the air filter and call it good.

That sounds like a ozone generator. I always advise against introducing ozone in to an occupied building. Ozone is a very caustic gas, that is why it can clean surfaces. Putting this system in a small room could elevate ozone to very high levels.

UV light by itself does not produce ozone or other byproducts. Its more like giving a deadly sunburn to the virus of bacteria.